1. Field of the Invention
The present invention relates to a film forming method and a film forming apparatus that forms an inter-layer insulation film and the like onto a semiconductor wafer in the semiconductor manufacturing steps.
2. Description of the Related Art
In a manufacturing step in a process of a semiconductor device, for example, SOD (Spin on Dielectric) system is used for forming an inter-layer insulation film. In the SOD system; a coating film is spin-coated on a wafer and an inter-layer insulation film is formed with performing processes like a chemical process or a heating process on the wafer.
For example, in a case of forming an inter-layer insulation film with sol-gel method, first of all, a solution in which an insulation film material is dispersed and dissolved into an organic solvent is supplied on a semiconductor wafer (hereinafter referred to as a xe2x80x9cwaferxe2x80x9d). Next a gelling process is performed on the wafer on which the solution is supplied by, for example, performing the heating process and the like.
Incidentally, manufacturing process of a semiconductor having a multi-level interconnection structure of recent years, a silicon oxide (SiO2) has commonly been used as a material for inter-layer insulation film and aluminum (Al) and the like has commonly been used as a material for wiring.
However, use of a copper (Cu) as a highly conductive wiring material for reduction of power consumed and use of, for example, an organic type insulation film (CmHn type), an inorganic film, an inorganic film on which hydrophobic process is performed, and a fluorine doped silicon oxide film (SiOF film) and the like has become increasingly popular for the purpose of realizing low dielectric constant.
In this case, an inorganic type silicon nitride (SiN) film is formed on a Cu film in order to prevent diffusion of Cu, and inter-layer insulation film such as aforesaid organic film, the inorganic film, the inorganic film on which hydrophobic process is performed, and a SiOF film are formed thereon.
However, there is a problem that adhesion of a low dielectric constant insulation film and an insulation film as an etching mask and a Chemical Mechanical Polishing stopper (CMP stopper) is poor and the low dielectric constant insulation film peels off when the Chemical Mechanical Polishing process (CMP process) is performed. In addition, the problem is not only the poor adhesiveness of an inorganic type film and an organic type film but also the poor adhesiveness of an organic type film and a resist film of the same organic type is also a problem in the process of forming an inter-layer insulation film.
Thus recently, a method of forming an adhesive layer of Silicon Oxide type (SiO type) between the films, and improving adhesion with utilizing chemical bonding strength is applied. However, since the adhesive layer in the method of using chemical bonding strength is very thin, bonding strength is not so strong, therefore, adhesive strength can not be improved greatly. In addition, when the adhesive layer is made thicker in order to increase chemical bonding strength, there is a drawback that the dielectric constant will become high. Thus it is not appropriate to make such adhesive layer with high dielectric constant thick from the point of view of inter-layer insulation film manufacturing process of producing multi-layer films of the present day.
Considering the above-described circumstances, an object of the present invention is to provide a film forming method and a film forming apparatus that improves an adhesion between low-dielectric inter-layer insulation films and the like and adhesion between an inter-layer insulation film and other neighboring films.
In order to accomplish the above-described objects, a first aspect of a film forming method of the present invention comprising the steps of performing a reforming process on a surface of a low dielectric constant insulation film formed on a substrate which includes one of a porous low dielectric constant insulation film and a non-porous low dielectric constant insulation film and forming an insulation film as at least one of an etching mask and a Chemical Mechanical Polishing stopper on the reformed surface of the low dielectric constant insulation film
In the present invention, for example, when plasma is radiated in order to perform a reforming process on a low dielectric constant insulation film such as an organic film, an inorganic film, an inorganic film on which a hydrophobic process is performed and a fluorine doped silicon film (SiOF film), a surface roughness of the organic film, the inorganic film, the inorganic film on which the hydrophobic process is performed increases and an adhesion with an insulation film formed as an upper layer of these films is improved by so-called an xe2x80x9canchor effectxe2x80x9d. In addition, as for the SiOF film, a density of fluorine on a surface thereof can be decreased, so that the adhesion with a low dielectric constant insulation film of organic type is formed as an upper layer.
On the other hand, surface roughness of a film is increased when, for example, an ultrasonic vibration is provided thereon as a reforming processing, and adhesion with an insulation film formed as the upper layer of the low dielectric constant insulation film is improved by so-called the xe2x80x9canchor effectxe2x80x9d.
A second aspect of the present invention is a film forming method comprising the steps of radiating plasma on a low dielectric constant insulation film and radiating an ultraviolet ray on the low dielectric constant insulation film after the plasma is radiated.
In the present invention, the surface roughness of the low dielectric constant insulation film is increased by radiating plasma and, in the same time, the adhesion between the insulation films can be improved more with a synergetic effect obtained from oxidation of the surface of the film caused by radiating an ultraviolet ray and radiating plasma. Here, with oxidation realized by radiating an ultraviolet ray, wettability on the surface of insulation film improves, in other words, the surface becomes hydrophilic and the adhesion can be improved. In addition, remote plasma is preferred when performing radiation with the plasma.
A third aspect of the present invention is a film forming method comprising the steps of performing a reforming process on a surface of an organic insulation film formed on a substrate and forming a film which includes an inorganic film and a Methyl-silsesquioxane film (MSQ film) as at least one of an etching mask and a Chemical Mechanical Polishing stopper (CMP stopper) on the surface of the reformed organic insulation film.
In the present invention, the reforming process is, for example, performed with radiating the ultraviolet ray. An adhesion with the organic film and an inorganic film, a MSQ film and a like formed on the organic film as an etching stopper and CMP stopper is improved with oxidizing the organic film so that the film becomes hydrophilic. Since the organic film does not have a polarity caused by OH group, the organic film is polarized to be hydrophilic by performing oxidization. As a result the adhesion can be improved. In addition, the surface reforming can also be performed with radiating plasma generated from N2H2 gas, so that the adhesion of an upper layer insulation film and a lower layer insulation film can be improved.
A first aspect of the present invention is a film forming apparatus comprising a coating portion coating an insulation film on a substrate, a reforming process portion reforming a surface of a coated insulation film and a transferring portion transferring the substrate between the coating portion and the reforming process portion.
In the present invention, since the transferring portion transfers the substrate between the coating portion coating the insulation film on the substrate and the reforming process portion reforming the surface of the insulation film, when a processing portion, for example, a heating portion is provided next to these coating portion, reforming process portion and transferring portion, processes like the coating process and the heating process and the like can be performed in sequence with the surface reforming process. As a result, through-put is improved.
A second aspect of the present invention is a film forming apparatus comprising a plasma radiating portion radiating a plasma on a surface of an insulation film and an ultraviolet ray radiating portion radiating an ultraviolet ray on the surface of the insulation film wherein the plasma radiating portion and the ultra violet radiating portion are integrated together structurally.
In such a structure, the surface reforming process performed with both radiating plasma and ultraviolet ray can be completed in one unit, leading to effective improvement in adhesion between the insulation films, in the same time, reduction in space and improvement in through-put.
A third aspect of the present invention is a film forming apparatus comprising a rotating portion rotating a substrate while holding, a supply portion supplying an insulation film forming material on the substrate while rotating the substrate with the rotating portion and a radiating portion radiating a plasma on the substrate while rotating the substrate with the rotating portion.
In such a structure, the supply portion supplying the insulation film forming material and the radiating portion radiating plasma are provided in the same chamber, which leads to reduction in space.
These objects and still other objects and advantages of the present invention will become apparent upon reading the following specification when taken in conjunction with the accompanying drawings.